The objective of this research project is to demonstrate the feasibility of utilizing a newly developed microporous material for vascular prosthetic applications, and also to study the various process parameters and their effect on the physical properties of the end product. An interpenetrating polymer network ("IPN") of polytetrafluoroethylene ("PTFE") and polydimethylsiloxane ("PDMS") is expanded using a stretching process which results in a microporous structure. Methodology will include blending, preforming, extrusion, expansion and sintering. This project is technologically innovative because the IPN composition is novel in several respects. PTFE/PDMS IPNs are capable of being expanded like ordinary PTFE, yet morphology, surface chemistry and physical integrity are atypical. These unique characteristics are believed to be well suited for general vascular prosthetic applications, and may offer discrete advantages for more difficult target applications such as small diameter prostheses.